Culverts, catch basins, and storm sewers are commonly used for collecting and conveying water. In some instances such water is discharged directly into the nearest available water body. This is considered undesirable due to potentially adverse environmental effects. Water management facilities have been constructed to help manage the quantity and quality of the water. Wet or dry retention or detention basins/ponds represent the most common structural approach to water management. Although more environmentally sound then direct discharge into an existing water body, such water management approaches preclude other uses of the land. This is of particular importance where land values are high and/or space is limited. The open ponds may also be undesirable in locations near airports because of birds attracted by the pond, or in locations where health, liability or aesthetic considerations make them undesirable. Even the use of “dry” detention basins frequently results in the same types of problems associated with wet ponds.
Underground systems have also been developed to help manage water and/or sewage system effluent. Those systems most commonly used include rows of large diameter pipe with a relatively small pipe protruding at the upper end of the pipe to retard flow for sediment deposition; infiltration trenches, which are basically excavations filled with stone and fed via drain pipes; and sand filters-typically large, partitioned concrete boxes with an initial compartment for sediment deposition and a following compartment with sand and under-drains for water filtration. Plastic arch shaped, open-bottomed water chambers are highly preferable to other types of underground water management systems for several reasons. They are typically less expensive, they are easier to maintain, they have a longer effective life. Also, unlike some other types of underground water management devices, plastic arch shaped open-bottomed water chambers can be located under paved areas.
In a typical installation of open-bottomed water chambers elongated hollow plastic half pipes are placed in the ground to form a leaching field for receiving water and gradually dispensing it into the surrounding earth. Such chambers have a central chamber for receiving inflow water. An open bottom allows water to exit the central chamber and disperse into the surrounding earth. The half pipes are usually connected together to form a multi-row array that constitutes a leaching field. The water is generally conducted to the array of rows by a large diameter header manifold pipe that runs orthogonal to the rows closely adjacent one extremity thereof, and the array looks something like an underground pipe storage system. Short feeder conduits convey the water from the header pipe to the end wall of the first chamber of each row. The pipes are generally engulfed in coarse backfill such as gravel or rock. Above the backfill is compacted soil and sometimes a paved cover surface. The resulting assembly may be used as a parking lot, roadway, sports field or for other uses.
The header pipe often comprise 12 or 24 inch diameter or larger high density polyethylene (HDPE) pipes with HDPE tees. It is not unusual for such a header pipe (manifold) system to be comprised of over 200 feet of HDPE pipe and 50 HDPE tees. A header pipe system of this type becomes very expensive and could easily add significant cost to the water management system and require significant additional area for installation.
In order to sustain the considerable downward forces imposed by the surrounding backfill and overhead vehicular traffic, the chambers are generally of arch-shaped configuration having a corrugated cross section. The corrugations consist of a continuous sequence of ridges or peaks separated by valleys so that the ridges and valleys extend on both sides of the pipe—inside the chamber and outside the chamber. The peaks and valleys are connected by web portions disposed in planes substantially orthogonal to the axis of elongation of the chamber. Examples of such corrugated pipes are found in U.S. Pat. No. 6,612,777 to Maestro, for example. However, the irregular interior walls of these storage chambers result in turbulence and secondary flow vortexes within the runoff being collected in the chambers from the surface. The turbulence and secondary flow vortexes leads to the uneven and random settling of sediments contained in the surface runoff throughout the length of the chambers. This uneven and random settling of sediments can therefore result in the accumulation of fine sediments. Moreover, corrugated pipes such as those disclosed in Maestro are made using a vacuum forming process which requires heating the raw material to a soft, substantially-molten state and then drawing a vacuum on the raw material to form the desired shape. The vacuum forming process greatly limits the ability to use strength enhancing additives in the half pipe.
It would be desirable to provide a water collection and storage assembly which reduces the problems resulting from of turbulence and secondary flow vortexes while maintaining the necessary strengths to support the weight of the earth and construction loaded above the pipes in the drainage area. It would also be desirable to provide a water collection and storage assembly which allows for the collection of sediments at specific collection points within the chambers so that the sediments could be easily accessible for removal through designated manholes.
From the foregoing disclosure and the following more detailed description of various preferred embodiments it will be apparent to those skilled in the art that the present invention provides a significant advance in the technology and art of water collection and storage assembly devices. Particularly significant in this regard is the potential the invention affords for providing a high quality, low cost, water collection and storage assembly with improved sediment removal. Additional features and advantages of various preferred embodiments will be better understood in view of the detailed description provided below.